Obviously, easier said than done, especially for urban communities. But I bet students could have better learning outcome, considering that indoor space are of

Obviously, easier said than done, especially for urban communities. But I bet students could have better learning outcome, considering that indoor space are often poorly ventilated and have an excess of CO2 https://www.nytimes.com/2019/05/06/health/conference-room-air.html https://www.nytimes.com/2019/05/06/health/conference-room-ai...